Direct laser deposition of Co-based alloys, specifically Stellite 6 and ERCOCR-B, was employed to enhance the tribological properties of hot-forging die steel – DIN 1.2714. The microstructure of the resultant claddings exhibited a refined microstructure consisting of an γ-Co matrix interspersed with hard phases, such as M 7 C 3 , M 23 C 6 , WC, and W 2 C, predominantly located at the grain boundaries. Microhardness analysis revealed that the Stellite 6 cladding achieved a maximum hardness of 472 VHN, whereas ERCOCR-B achieved 539 VHN. The tribological performance of the claddings was analysed using a ball-on-disc tribometer at varying temperatures – ambient temperature, 450°C, and 550°C. Both claddings significantly outperformed the base material, with the improvement attributed to the existence of hard carbide phases. Notably, ERCOCR-B demonstrated superior wear resistance, reducing wear volume by 97.2% at ambient temperature, 90.8% at 450°C, and 62.5% at 550°C. Stellite 6 claddings exhibited 59.6% at ambient temperature, 79% at 450°C, and 48.5% at 550°C lower volume loss than substrate. The observed wear mechanisms included adhesive, abrasive, and oxidative interactions, with their extent varying with temperature and coating type.
Raj et al. (Tue,) studied this question.